Ah, but you were pricing N2 gas, try it again with liquid nitrogen, a hundred litres or so of N2(liquid) is a LOT of gas when you warm it up, even at a few bar.
LN2 has a density of ~800g per Litre, N2 gas at STP has a density of 1.25g per litre so 1L of LN2 makes 640 litres of gas at STP, or 64L of gas @ 10 Bar.
Most of the costs at these small volumes are actually service charges, N2 as liquid is cheaper then water in some places if you buy it in industrial quantities.
Not going to be cheaper then air from a good quality screw compressor, but it will probably have lower capex.
You will want a dewar designed for pressurised delivery and some sort of heat exchanger to boil the liquid.
regards, Dan.